Kelvin Probe Measurement of Corrosion Poteitial of Low-Alloyed Steels and the Thickness of Electrolyte Layer during Cyclic Corrosion Condition

Abstract

Kelvin probe measurement was applied to measure corrosion potential of low-alloyed steels covered with thin electrolyte layer (0.1mM NaCl) and the thickness of electrolyte layer. A good correlation between the volta potential difference between gold Kelvin probe and working electrode (low-alloyed steel) and its electrochemical corrosion potential was observed. By Kelvin probe measurement, variations of corrosion potential and the electrolyte thickness was successfully monitored. In case of the working electrode covered with corrosion products, diminution rate of electrolyte layer was decreased at about 50μm, which are considered to be the effects of corrosion products “on time of wetness of specimen”. Below about 200μm of the electrolyte layer thickness, corrosion potential shifts cathodically according to the diminution of the thickness of electrolyte layer up to a few μm, which suggests the break down of passive film is occurred by chloride concentration.